1. Field Of The Invention
The present invention concerns biosensers, i.e. sensors for detecting and/or monitoring or quantifying the presence and/or behavior of specific species in test fluid samples. The invention is applicable to the following: immunoassays, i.e.; the detection of antibodies, antigens, or hormones in blood samples; pollution monitoring; and, to the monitoring of clinical diagnostic reactions involving enzymes and the like.
2. Description of Related Art
A recent article entitled "Detection of Antibody--Antigen Reactions at a glass-liquid Interface as a Novel Optical Immunoassay Concept", (1984), R. M. Sutherland et al (Proceedings of 2nd Optical Fibre Conference (Stuttgart 1984) page 75) describes a biosensor in which an antibody species is covalently immobilized onto the surface of a planar or fibre-optic waveguide. The reaction of immobilized antibody with antigen in a sample solution is detected using the evanescent wave component of a light beam which has been totally internally reflected many times within the waveguide. The evanescent wave has a characteristic penetration depth of a fraction of a wavelength into the aqueous phase, thus optically interacting with substances bound to or very close to the interface and only minimally with the bulk solution.
Reference is also made to our United Kingdom Patent Application BG 2156970A published Oct. 16, 1985, which discloses optic-waveguide biosensors and a similar technique. The content of that disclosure is incorporated herein by reference.